Ribbon feeding and reversing mechanism for adding machines



RIBBON FEEDING AND REVERSING MECHANISM FOR ADDING MACHINES G. QLBARRETTJan. 13 1931.

Original Filed Aug. 1925 3 Sheets-Sheet 1 Q mm x H w. H 3 m M 7 F AddINVENTOR ennJBarratt.

'- s l I ATTORNEYS Jan-1.13, l931. G. J. BARRETT 7 RIBBON FEEDING ANDREVERSINIGIMYECIIANIS'M For: ADDING MACHINES OriginaIFT-led Aug. 14,1925 .3 Sheets-sheaf. 2

INVENTOR Glenn Jiarrett.

ATTORNEYS Jag. 13,1931; v J BARRETT 1,788,376

RIBBON FEEDING AND REVERSING MECHANISM FOR ADDING MACHINES I OriginalFiled Aug. 14, 1925 3 Sheets-Sheet 3 INVENTOR ATTORNEYS V Patented Jan.l3, 1931 UNITED STATES PATENT OFFICE GLENN BARRETT, EVANSTON, ILLINOIS,ASSIGNOR TO--'.PORTABLE ADDING MA- CHINE COMFANY, 0F SYRACUSE, NEW YORK,A CORPORATION OF ILLINOIS RIBBON FEEDING AND nnvnnsnve Mncrmmsm ronADDING MACHINES Original application filed August 14,1925, Serial No.50,219; Divided and this application filed June 9,

This invention relates to improvements in listing or printing mechanismfor adding machines and'has for its principal objects to provideimproved means for feeding and reversing the inked ribbon of theprinting mechanism and to provide efficient means for feeding areeled'inked ribbon intermittently passing the impression line of themachine and pressing the same against the. types at the impression linethrough the medium of a platen and a vibratory platen support which iscontrolled from the general operator of the machine to shift the platentoward and from the type at each actuation of the general operator.

To the foregoing and other ends, which will appear from 'the followingdescription in detail of the preferred embodiment of the invention, theinvention consists in the features of construction, arrangement ofparts, and combinations of devices set forth in the specification andparticularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a rear View of the machine sub stantially perpendicular to theprinting plane with the operating parts positioned as in Fig. 5;

Fig. 2 a fragmentary central longitudinal sectional view. of the machineshowing the ribbon mechanism in elevation as viewed from the right handside of the machine;

Fig. 3 a fragmentary view of the machine showing the ribbon mechanismand part of the platen support in elevation as viewed from the left handside of the machine; p

Fig. 4 a vertical sectional view of the rear part of the machine casing,showing the ribbon mechanism and the platen operating:

mechanism in side elevation;

Fig. 5, a fragmentary vertical sectional view showing the platen inprinting and ribbon feed operating position; I

' Fig. 6a detail erspective'view of the ribbon guidingbrac et;

Fig. 7 a top plan view of the ribbon mechanism, partly broken awaythrough the upper spoolfshowing the actuating arm of the dog carrierinits normal rear position and the feed-reversing mechanism in positionfor Serial No. 284,100.

sitionshown in Fig. 11;

Fig. 8 a view similar to Fig; 7 but showing the actuating arm of the dogcarrier in its forward position, as at the end of the forward stroke ofthe operating handle of the machine, ready for effecting afeed movementof the ribbon on the return stroke;

Fig. 9 a top plan view of the ribbon mechanism with the parts above thedog carrier broken away and the dog carrier positioned as in Fig. 8;

Fig. 10 a view similar to Fig. {7 showing the reversing mechanism set toreverse the direction of feed on the next forward stroke of theactuating arm of the dog carrier to cause winding of the ribbon from thelower spool on to the upper spool;

Fig. 11' a view similar to Fig. 9 showing the reversing mechanism set toreverse the directional? feed on the return stroke of the actuating armof the dog carrier to cause Winding of the ribbon from the upper spoolOnto the lower spool;

Fig.12 a perspective view of parts of the ribbon reversing mechanism andtheir supporting bracket detached;

13 a detail View on the line 1313 of Fig. 11 showing the detent meansfor locking the feed reversing cams-to rock with the dog carrier.

This application is a division of my 00- ;pending application, SerialNo. 50,219, filed August 14:, 1925, for improvements in adding machines,and only so much of the machine shown and described in said co-pendingap-- plication as is necessaryfor a fullunderstanding'of the subjectmatter claimed inof the machine, exceptthe ribbon mechanism, fingers155, adapted to co-operate with a which, as hereinafter described, ismounted on a cover casing 8.

Casing 8 has an open bottom to enable it to be fitted over thesupporting framework and enclose most of the working parts of themachine, and said casing is held in place by screws or otherwise;

The top wall of easing 8 has an upwardly and rearwardly extending frontportion and a downwardly and rearwardly extending rear portion extendingto the upper end of the'rearvertical wall of the casing. downwardly andrearwardly inclined top wall portion is provided with an aperture 11through which extends a rocking platen support mounted on the frameworkas hereinafter described. The types of the printing segments 69 when setside by side in the printing plane face upward and rearward and areexposed through aperture 11, and the platen 141 is movable forward anddownward through said aperture against said types to take animpressiontherefrom as shown-in Fig. 5. The ribbon feeding, reversing,and guiding means are mounted on the downwardly and rearwardly extendingtop wall portion of easing 8.

Pldten sapportz'ng means The type 70 on the respective type segments 69are rigidly held to the segments and face radially outward toward therear and are adapted to be printedon by the platen 141, which is mountedfor movement toward and from the type segments. The platen 141 has itsshaft 159 rotatably mounted in platen frame plates 142, which aresecured together by transversely extending stay rods 143, 144 and 145,to form a rock-' ing'frame, which is mounted upon a transverselyextending rock shaft 146 located adjacent the rear wall of easing 8 andjournalled in the frame side plates 5. The platen frame side plates 142extend up through aperture 11 in casing 8 and may be secured to orotherwise adapted to be rocked by rocking the shaft 146, but preferably,a hub 147 1s mounted on the rock-shaft 146 'as indicated in Fig. 5 ofthe drawings, and rigidly'secured thereto in any suitable manner. Thehub is provided with a depending arm 149 The transversely extending stoprod 156, for limiting the movement of the platen toward the typesegments under the action of the operating handle, as hereinafterdescribed. The stop rod 156 is preferably adapted to be adjusted up anddown by being mounted in vertical slots 157 in main frame side plates 5,as shown in Figs. 4 and 5, the stop rod being held in adjusted positionby suitable clamping screws 158. By means of this adjustment, thepressure of the platen against the type 70 of the-type segments may beregulated.

Ribbon meal: anz'sm To provide a satisfactory ribbon mechanism formachines of this type is a difficult problem, particularly as the spaceis limited and it is desirable to provide not only for the satisfactoryfeeding of the ribbon, but also to providefor the automatic reverseofthe feed, which will not require any attention on the part of theoperator. I have provided a compact and simple ribbon mechanism operabley the shifting platen frame. A bracket 329 for the ribbon mechanism ismounted on the rearwardly and downwardly inclined rear portion of thetop wall of the cover casing 8 at the left hand sideedge of aperture 11in the casing and secured to said portion of the casing by suitablescrews 330, as indicated in F 3 of the drawings. The bracket 329 isprovided at its lower edge with an upwardly and rearwardly extendingplate 331,

provided with a rod or shaft 332, projecting laterally therefromupwardly and forwardly and forming the axle for a pair of ribbon spools333 and 334, which are held in place thereon by suitably spaced sealingclips (not shown) and a screw 335, threaded in the end of the axle rod332 and cooperating with a washer 336 The ribbon spools 333 and 334 arespaced apart on the axle 332, and pivotally mounted therebetween on saidaxle is a ribbon feed dogrocker 337 provided with a laterally projectingrock-arm 338. The rock-arm 338 is provided with an ear 339 adapted to beepgaged and rocked forward by a pin or stud 340, projecting from theleft hand platen-rocking frame plate 142, to rock the dog rocker aboutaxle 332 to the position shown in Figs. 8, 9 and 11 from its normalposition shown in Figs. 7 andlO. A rearwardly projecting ear 341 on thedog rocker is provided with two feed dogs 342 and 343, pivotally mountedthereon on a stud 344, the feed dogs being adapted to cooperate withratchet teeth 345, formed on the peripheries of adjacent spool flangesof the ribbon spools 333 and 334. The dog rocker 337 is provided with anarm 346 projecting laterally outward and provided with a hole 347 in theend thereof, in which one end of a dog-rocker return spring 348 issecured. The opposite end of the spring 348 is secured to a laterallyprojecting lug 349'on the base of a small bracket 355 secured tothe'base of bracket 329', as indicated in Figs. 7 and 11 The dog-rockerreturn spring 348 is adapted to restore the dog rocker tonormalposition, shown in Fig. 7 after it has been moved or rocked to theposition shown in Fig. 8 .by engagement of the pin 340 on theplaten-rocking frame with the dog rocker ear 339. The dog rocker 337 isfurther providedwith a stop finger 350 adapted to engage a rod 351 heldto bracket 329 parallel v with axle rod 332 to thereby limit the reinits normal or. at rest position, as shownin- F1g. 10. The detent dogs353 are preferably turn movement of the dog rocker under the action ofthe spring 348. The noses 358 of dogs 342'and 343 areadapted to be urgedtoward the ratchet teeth 345. ofthe respective ribbon spools by means ofsprings 352 connected'to the respective dogs and to the dog rocker arm346 in the hole 347, as indicated in Figs. 1, 3, 8 and 9.

Detent dogs 353 are pivotally mounted on a rod'354 mounted in the earsof the small bracket 355, secured to the main ribbon supporting bracket329, the detent dogs'being' ing'ends 357 ,adapted'to lie above thelaterally bent noses 358 of the. respective feed dog's 342 and 343, sothatwhen the feed dog of either spoolis lifted out of operative relationwith the teeth of the corresponding ribbon spool, the detent dog 353associated therewith will also be lifted out of the field of the ratchetteeth, when the dog-rockeris resilientlycheld in cooperative relationwith the feed dogs and ratchet teeth of the re spective ribbon spools bymeans of suitable springs 359 connecting the detent dogs with ribbonfollowers of the automatic feed reversing means as hereinafterdescribed.

In order to provide means for holding one or the other of the ribbonfeed dogs 342-343' out of operative engagement-with its =corre-'sponding ribbon spool, a pair of cam (plates 360 and 361 are mountedupon the axle 332, one on each si e of the dog rocker 337.

l The cam plate 360 is, 'provided with a cam edge 362'having a dwellportion at one end and cooperating with the nose 358 of the'feed dog342, while the cam plate'361 is provided with a cam edge 363 having adwellp'ortion at one end and cooperatin with the bent end 358 of thefeed dog 343. he two cam plates 360 and 361 are rigidly secured togetherby a tie rod 364, so that when cam plate 361 is moved about axle '332 bymeans-of an outwardly ,projectin manual ribbon-reversing finger piece365, ormed as part thereof, the other cam plate 360 will also bemoved,and

the arrangement is such that when the cam edge 363 is moved under itsdog, the cam edge 362 will be moved out from under its dog, therebypermitting the latter to operate in the ratchet teeth 345 of its ribbonspool, for feeding action of the ribbon, when the dog rocker 357 is oerated.

Obviously t e cam plates 360 and 361 should rock with the dogrocker'337, in orderto maintain one of the feed dogs 342 and 343 inoperative position and the other feed dog in noperative position and,therefore, a detent; operating between the cam plates-and the dog rocker337 is provided consisting of a spring pressed pin 366 in the dog rocker337, coo'perating with two positi'onin'gholes 366, located in the camplate- 360. When the cam plates of the duplex cam, arejnthepositionsshown in Figs. 7, 7 and 7 thedwell of cam edge 362 is underthe nose 3580f the dog 342, ahd the nose of said dog 342and the detentpin 356 of the corresponding detent dog 353 are held out of co-opera-.tive relation with the ratchet teeth 345 of the cam' 361 and is in engaement with the' ratchet teeth 345 of the rib on spool1334' andthe'detent pin 356 of the corresponding detent dog 353 is in engagementwith its associated} ratchet ,teeth 345r With the parts inthQSQ'POSltiODS the ribbon 376 will be wound on the upper spool 334.When the cam plates are shifted in the direction indicated by the arrowsin Figs. 7 and 7 to the position shown in Fig. 10, the dwell of cam edge363 is enga ed under the'nose 358 of dog 343 and holds t e nose of saidfeed dog and the detent pin 356 of its corresponding detent dog 353outof operative relation with the ratchet teeth 345 of the upper spool334. The dwell portion 362 of cam plate 360 will be moved= away from thenose of'dog 342 and said nse will engage its associated. ratchet teeth.With the parts 'in this shifted position the ribbon 376 wll be wound onthe lowery spool 333. The feeding or spool-rotating action of the dogrocker 337 always takes place under the a9t101l0f the dog-rocker returnspring 348 upon the return movement of the platen- ;rockh1g frame, thereturn movement of the dog-rocker being limited by engagement of thefinger 350 with the shaft. 351, The ribbon spool associated ,with theinactive feed dog is always the let-ofi spool and the ribbon spoolassociated with the active feed dog is the take-up spool. When the dogcarry- .ribbon spool 333. The nose 358 of the dog 343 is leased from thedwell portion 363 of the let-o ing lever is actuated, the active detentpin 356 holds the ratchet of the take-up spool against rotation inlet-ofi' direction, but permits it to rotate under the action of thefeed dog in take-up direction. The inactive detent pin 356 drops intoengagement with its associated ratchet teeth after the dog carryinglever has been moved slightly and thereby locks the let-off spoolagainst movement in letoif direction. On the return movement of the dogcarrying lever the active feed dog immediately acts upon the take-upspool and starts its rotation to take up the ribbon. During the firstpart of this movement the active ,detent is in engagement with thelet-ofl' spool and locks said spool against movement in' let-oifdirection. This permits the take-up spool to take in any slack in theribbon be-- tween the spools before the let-off spool is released. Whenthe inactive feed dog engages the inactive detent dog upon the returnmovement of the dog carrying-lever, the let-off spool is released andthe take-up spool may thereafter draw the ribbon from the spool. Thisensures a tight ribbon through the ribbon guide and between the tworibbon spools. If there is any slack in the ribbon between the twospools there will be very slight, if any, movement of the letoff spooluntil after all of the slack has been taken up.

An automatic ribbon reverse is an exceedingly desirable feature, inmachines of this character, for the machine may be operated indefinitelywithout requiring the operator to watch the ribbon and reverse the feedthereof when necessary. Therefore, in connection with my improvedribbonfeed mechanism, I have provided an automatic reverse, whichcomprises means for automatically shiftin the cam plates 360 and 361,through the me iumiof the dog rocker operated-by the platen-rockingframe.

For this purpose, ribbon-following fingers 367 are pivotally mounted onthe shaft 351 dogs 369 and 370 respectively carried on the hubs of thefollowing fingers of the upper and lower spools and providedrespectively with oppositely extending ears 371 and 372. The'cam plates360 and 361 are provided with operating fingers 374 andrespectivelyvadapted; to cooperate'with the ears.371 and 372, when thelatter are thrown into the paths thereof by movement toward the centerof the spools of the associated following fingers 367. As will be seenin Fig. 12, the cam operating finger 373 is provided with a squared end,adapted to abut against the car 371 when said ear is moved outward inits path, as shown in Fig. 10, while the cam finger 374 is provided witha hook end 375 adapted to hook under the ear 372 when said ear is thrownoutward into its path, as shown in Fig. 11. i

It will be recalled that the rigidly connected cam plates 360 and 361,carrying the respective operating finger-S374 and 373, are yieldablylooked to rock with the dog rocker 337, each time the dog rocker isoperated by the pin 340 on the platen-rocking frame. Hence, when theautomatic reversing mechanism is set by substantial exhaustion of theribbon from the upper spool 334 in the position shown in Fig. 10, withthe ear 371 moved outward so as to 'lie in front of the end of thefinger 373 of cam plate 361, the parts are in position to reverse thefeed when the rock arm- 338 is operated by the pin 340. Vhen the dogrocker 337 is rocked by the pin 340 it will move asusual to the positionshown in Fig. 8 but the cam plates 360vand 361 will be prevented frommoving therewith at this time by the engagement of the operating fin-9'01 373 with the 'dog ear 371; thus the cam plates will be shiftedrelatively to the dog rocker and dogs and the cam 362 will be broughtinto the position shown in Fig. 9 to lift the feed dog 342 upon thedwell of cam edg'e 362, thereby preventing further rotation of theribbon spool 333 by said dog,

while the cam edge 363 of cam 361 will be withdrawnfrom support of thedog-343 and the latter, under the pull of its sprmg 352,

"will be brought into feeding relation with the corresponding ratchetteeth 345 of its ribbon spool 334, asindicated in Figs. 7 and 8. Whenthe following finger 367 ofthespool 333 reaches the position shown inFig. 11, that is, when the spool becomes nearly empty, the correspondingdog 370 is moved outward to bring its ear'372 into the throat of hook375 of the operating fingerc374 carried by the cam plate 360, as shown,so that, upon the plates 360 and 361 from movement with the 1 dog rockerat this time, thereby shifting the relative position of the cams and dogrocker and placing the dwell of cam edge 363 under the nose of the dog343, thus lifting the latter,

and its cooperating detent dog 353, out of cooperative relation with thecorresponding ratchet teeth 345 of the spool 334. while cam edge 362will be withdrawn from the nose of .dog 342 to permit the said dog andits detent to cooperate with the teeth of spool 333 and thereby againreverse the feed.

The ribbon 376 is carried between'the respective ribbon spools over aribbon guide plate 377, which is'mounted, b means of ears 378, on therearwardly and v ownwardly slanting portion of the cover casing 8, asshown in Fig. .1, the ears 378 being located in depressions37 9 in thecover casing at the horizontal upper edge of the opening 11 therein. Theribbon guide 377 is secured to the casing 8 by suitable screws whichpass through the ears 378, so as to lie across the upper part ofaperture 11 in a plane parallel to the printing plane of the types 70 ontype segments 69 whenjat the printing line. The ri bon 376 is-adapted toass throu h two aligned slots 381 at the left hand on of the guide plateand over two right angle direction changin end of said p ate so that theribbon will pass from one spool to the other and lie in parallel bandsextending from the spools over the ribbon guide across the aperture 11,the

lower band of the ribbon passing over the printing line of the types, sothat it is adapted to be between set types and the aper when the platenis moved forward in t e printing operation. The upper ribbon spool 334of the ribbon mechanism is preferably provided with a small knob 383formanua 1y winding the ribbon, when it is necessar to do so, for

instance, in taking out an o d ribbon and putting in a new one.

Platen support operating men/as eration. For this purpose, a link orpit'man' 222 is pivotally mounted on a stud 223 carried by the cam disk201 and normally located forward of the axis of rotation of the main orhandle shaft 68 on which the disc is fixed, as indicated in Fig. 4, thelink normally extending downward and rearward from. said stud at such ananglethat the disc and link have a toggleaction whidh brin s the pivot223 substantially into a straight ine between the shaft 68 and the rearend of thelink when the handle is at the forward end of mounted forslight adjustment and secured in place by a lock nut 225. The inwardlypro ec ting endojf stud 224 is adapted to normally ride in an.elongated-notch or opentop slot 226 in the lower extremity of a crankarm 227, secured to the outer end of the platen framerock shaft 146, thearrangeto g e action, of the disk and edges 382' at the righthandlostmotion during the first part of the forward stroke of the handle 196before the stud 224 will engage-the rear end of the open slot 226 androck the platen frame to swing the laten toward the printing point. The

end-of the forward stroke of handle 196, as

the pivot 223 brin s the link or pitman to dead center, will oroe theplaten against the type segments or pressure printin upon the paperstrip 1 8 of those numera types on the segments that stand at the rintmgline. The-amount of pressure re uired for printing varies with thenumber 0 segments to be printed from, and the ad'ustment of the stud 224is adapted to be ma e according nk, near the to the pressure required.It has been previously pointed out, however, that in order to positivelylimit the movement of the platen against the type segments, the lowerext-remities 155 of the platen rock frame are adapted to engage thetransversely extending stop rod 156 to thereby prevent excessive.pressure when only a few type' segments are to be printed from. The linkor pitman 222 and. its stud 224 are preferably held in proper relationwith the open slot 226 in the crank arm 227, bya vertically slottedbracket plate 228 secured to the side of the crank arm 227 the slotbeing elongated to allow u ward movement of the rear end of the link. 11the return stroke of the operating handle 196 the platen-frame restoringspring 154 returns the platen and its frame to normal position and holdsit there as. hereinbefore described.

'It is frequentlydesirable in machines of this type to operate themachine without printing the numbers, and this is usually effected byproviding a special mechanism op-. erated or controlled by a non-printkey. In the present instance it will be seen' that if the stud 224 atthe end of the abutment or line 222 is lifted out of the open slot 226the rock arm 227 will' not be operated on the forward stroke of thehandle and, hence, the platen will not be moved forwardfor rinting. Inmy co-pending application, Ser al No. 50,219 this non-print mechanismand the key for op.- crating itis fully shown and. described Ob viouslone advantage of operating the ribbon eeding mechanism by means of' theplaten-rocking frame 142, is that, when the non-print key is depressedto eliminate the printing of a number by preventing rocking of theplaten frame, operations of the ribbon feeding mechanism areautomatically eliminated at the sametime.

What I claim is: v 4 1. In a key set adding 'a'ndlisting machine 'thecombination of a main frame, a general operator for the machine, typesadapted to beset in a printing plane, a casing for the machine havingatop wall the rear portion of which extends downwardand rearwardann] isprovided with an aperture through which types in the printing plane areexposed, a

platen located above the lower part of said substantially parallel withthe printing plane, a rocking support mounted on the main frame andextending up through said aperture and in which the platen isjournalled, means operablefrom the general operator for rocking saidsupport to swing the platen forward and downward through said' apertureagainst types in theprinting plane, and means for actuating the ribbonfeeding mechanism from the rocking platen support. 2. In an addingandlisting machine, numeral types, a platen, a shiftable su port onwhich the platen is mounted, means or shifting said supportto vmove theplaten to and from the type for'taking an impression therefrom, an axlemounted independently of the platen support, a pair of ribbon spoolsrotatably mounted on said axle, means for guiding a ribbon between saidspools between the platen andthe impression taking positionlof, thetypes, said spools having ratchet teeth' thereon, a dog-carrying leverpivotally mounted on said axle between the spools, a

' pair of feed dogs pivoted on said lever for cooperation-with theratchet teeth of difierent spools to turn the spools, means for holdingone dog out of action when the other dog is operable on the teeth of itsassociated spool, said dog-carrying lever being movable in one directionby the ,platen support, a spring for restoring, said lever, and stomeans-determining the normal position 0 the lever.

3.; An adding and listing machine l as claimed in claim 2, wherein themeans for holding one feed'dog at a time out of action comprises aduplex cam rotatably mounted on the axle rod having tworigidly connectedcam members effective on the respective feed dogs to hold one dog out ofaction and permit the other dog to act, and a spring detent device forreleasably holding the duplex cam to;

the dog carrier in either of two feed-rovers" ing positions to rock withthe dog carrier.

4. An addlng and listing machine as 'claimed in clym 2, wherein themeans for holding one i ed dog at a time out of action comprises aduplex cam rotatably mounted onthe axle rod having two rigidly connectedcam-members effective on the respective feed dogs to hold one dog out ofaction and permit the other dog to act, a spring detent device forreleasably holding the duplex cam ly to the dog rocker between saidfeed-reversing positions upon actuation of the dog carrier.

5. An adding and listing machine as claimed in claim 2, wherein detentdogs associated with the respective spool ratchets are provided, each ofsaid detent do s being held by its associated feed dog out 0 action whenthe feed dog is held out of action and in its at-rest' position.

6. An adding and listing machine as claimed in claim 2, wherein themeans for holding one feed dog at a time out of action comprises aduplex cam rotatably mounted on the axle rod having two rigidlyconnected cam members ,efiective on the respective feed dogs to hold'onedog out of action and permit the other dog to act, a springdetent-device for releasably holding the duplex cam to the dog carrierin either of two feed-reversing positions to rock with the dog carrier,and two pivotally mounted devices one for each ribbon spool, each ofsaid devices being provided with one arm adapted to bear on the ribbonroll of its associated ribbon spool and with another arm adapted toswing into the path of an arm on one member of the duplex cam when theribbon is exhausted from said spool, whereby the actuation of the dogcarrier-when the ribbon is exhausted from one spool will cause arelative movement bevice for releasably holding the duplex cam to thedog carrier in either of two feed-reversing positionsto rock with thedog carrier, and two pivotally mounted devices one for each ribbonspool, each of said devices being provided with an arm adapted to bearon;

the ribbon roll of its associated ribbongspool and with another armadapted to swing into the path of anarm on one member of the duplex camwhen the ribbon is exhausted from said spool, whereby the actuation ofthedog carrier when the ribbon is exhausted from one spool will cause arelative movement between the duplex cam and the dog carrier and therebyreverse the feed of the ribbon, one of said devices operating to effectrelative movements between the dog carrier and the duplex cam' upon theactuation of the dog carrier in one direction and the other operatingwhen the dog carrier is moved in the opposite direction to effect thefeed reversingoperation.

8. In an adding and listing machine, numeral types, a platen, ashiftable supporton which the platen is mounted, means for shifting saidsupport to move the platen to and from the type for taking an impressiontherefrom, an axle-mounted independently of the platen support, a pairof ribbon spools rotatably mounted on said axle, means for guiding aribbon between said spools between the platen and the impression takingposition of the types, said spools having ratchet teeth thereon, adog-carrying lever pivotally mounted on said axle between the spools, apair of feed dogs pivoted on said lever for cooperation with the ratchetteeth of differ ent spools to turn the spools, means for holding one dogout of action when the other dog is operable on the teeth of itsassociated spool, said dog-carrying lever being movable in one directionby the platen support, a spring for restoring said lever, stop meansdetermining the normal position of the lever, means to lock the let-offspool from movement in letoff direction, and means to release said lookafter the take-up spool has made a part .of its take up movement.

9. In an adding and listing machine, the combination of a generaloperator, a platen, a platen support shiftable by the general operatorto and from an impression-taking position, types adapted to be engagedby the platen when the platen support is shifted into impression-takingposition, means'for feed- :ing an inked ribbon between theimpressiontaking plane of the types and the platen operable by shiftingmovement of the platen support; and a feed reversing meanssettable bythe ribbon for actuation by shifting move; ments of the platen support.I

.10. In an adding and listing machine, numeral types adapted to be setfor printing, a platen, a shiftable support on Which the platcn ismounted, means for shifting the support to move the platen to and fromset types for taking an impression therefrom, means mountedindependently of the platen support and operable by the shiftingmovements thereof for feeding an inked ribbon between.

the platen and the impression-taking position of the types, andribbon-controlled feed reversing means adapted to be set in operativeposition in the path of a part of the ribbon feed means by. theexhaustion of the ribbon from one of the ribbon spools, whereby theoperation of the ribbon feeding means by the shifting movement of theplaten support will operate the ribbon reversing means when said meansis set in operative position by the exhaustion of the ribbon from oneribbon spool. v

11. In an adding/and listing machine, nu

meral types adapted to be set for printing; a platen. a shiftablesupport on which the platen is mounted, means for shifting the supportto move the platen to and from set types for taking an impressiontherefrom; a pair of ribbon feed dogs; means mounted independently ofthe platen support and operable by the shifting movements of the platensupport for actuating the feed dogs to feed an inked ribbon between theplaten and the impression taking position of the types aribbon-following finger for each ribbon spool adapted to move toward andfrom the spool center as the reeled portion of the ribbon on the spoolincreases or decreases in diameter; a ribbon reverse dog connected toand movable with each following finger and adapted to be set inoperative position bythe exhaustion of the ribbon from its associatedribbon spool; and a feed dog-positioning cam for each ribbon feed dog,rockable with the ribbon feed mechanism and adapted to be brought intoengagement with the set ribbon reverse dog when the ribbon feedmechanism is operated by the shiftable platen support, to therebyreverse the position of the ribbon feed dog.

12; An adding and listing machine as claimed in claim 2, combined with adetent dog associated with each spool ratchet and adapted to be engagedby and swung outwardly away from its associated spoolratchet by itscooperating feed dog when said feed dog is moved out of the path of theratchet teeth; a rockable duplex cam having two members engaged with thefeed dogs and adapted to move one of said dogs into engagement with itsspool ratchet and to move the other feed dog out of engagement with itsassociated ratchet when the-duplex cam is rocked in one direction, andto reverse the positions of the feed dogs when rocked in the oppositedirection, whereby the inactive detent dog will be free to engage itsassociated ratchet after the dog carrying lever has made a partialmovement under the action'of the shiftable platen support and wherebyupon return movement ofthe dog carrying lever the active feed dog willslightly move the take-up spool before the inactive feed dog moves thedetent from the let-off spool.

In testimony whereof I hereunto aflix my signature,

l GLENN J. BARRETT.

